Organic anti-reflective coating material and its preparation

ABSTRACT

Polymers are provided having the following formula I, II or III:  
                 
 
     Polymers of the present invention can be used to provide an anti-reflective coating (ARC) material useful for submicrolithography processes using 248 nm KrF, 193 nm ArF and 157 nm F 2  lasers. The polymers contain chromophore sub substituents which exhibit sufficient absorbance at wavelengths useful for such submicrolithography process. The ARC prevents back reflection from the surface of or lower layers in the semiconductor devices and solves the problem of the CD being altered by the diffracted and reflected light from such lower layers. The ARC also eliminates the standing waves and reflective notching due to the optical properties of lower layers on the wafer, and due to the changes in the thickness of the photosensitive film applied thereon. This results in the formation of stable ultrafine patterns suitable for 64M, 256M, 1G, 4G and 16G DRAM semiconductor devices and a great improvement in the production yield.

CROSS-REFERENCES TO RELATED APPLICATIONS

[0001] This application is related to Korean Patent Application No.99-14763, filed Apr. 23, 1999, and takes priority from that date.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to an organic anti-reflectivecoating material which allows the stable formation of ultrafine patternssuitable for 64M, 256M, 1G, 4G and 16G DRAM semiconductor devices. Moreparticularly, the present invention relates to an organicanti-reflective coating material which contains a chromophore with highabsorbance at the wavelengths useful for submicrolithography. A layer ofsaid anti-reflection material can prevent back reflection of light fromlower layers or the surface of the semiconductor chip, as well aseliminate the standing waves in the photoresist layer, during asubmicrolithographic process using a 248 nm KrF, 193 nm ArF or 157 nm F₂laser light sources. Also, the present invention is concerned with ananti-reflective coating composition comprising such a material, ananti-reflective coating therefrom and a preparation method thereof.

[0004] 2. Description of the Prior Art

[0005] During a submicrolithographic process, one of the most importantprocesses for fabricating highly integrated semiconductor devices, thereinevitably occur standing waves and reflective notching of the waves dueto the optical properties of lower layers coated on the wafer and tochanges in the thickness of the photosensitive film applied thereon. Inaddition, the submicrolithographic process generally suffers from aproblem of the CD (critical dimension) being altered by diffracted andreflected light from the lower layers.

[0006] To overcome these problems, it has been proposed to introduce afilm, called an anti-reflective coating (hereinafter sometimes referredto as “ARC”), between the substrate and the photosensitive film.Generally, ARCs are classified as “organic” and “inorganic” depending onthe materials used, and as “absorptive” and “interfering” depending onthe mechanism of operation. In microlithographic processes using I-line(365 nm wavelength) radiation, inorganic ARCs, for example TiN oramorphous carbon coatings, are employed when advantage is taken of anabsorption mechanism, and SiON coatings are employed when aninterference mechanism is employed. The SiON ARCs are also adapted forsubmicrolithographic processes which use KrF light sources.

[0007] Recently, extensive and intensive research has been and continuesto be directed to the application of organic ARCs for suchsubmicrolithography. In view of the present development status, organicARCs must satisfy the following fundamental requirements to be useful:

[0008] First, the peeling of the photoresist layer due to dissolution insolvents in the organic ARC should not take place when conducting alithographic process. In this regard, the organic ARC materials have tobe designed so that their cured films have a crosslinked structurewithout producing by-products.

[0009] Second, there should be no migration of chemical materials, suchas amines or acids, into and from the ARCs. If acids are migrated fromthe ARC, the photosensitive patterns are undercut while the egress ofbases, such as amines, causes a footing phenomena.

[0010] Third, faster etch rates should be realized in the ARC than inthe upper photosensitive film, allowing an etching process to beconducted smoothly with the photosensitive film serving as a mask.

[0011] Finally, the organic ARCs should be as thin as possible whileplaying an excellent role in preventing light reflection.

[0012] Despite the variety of ARC materials, those which aresatisfactorily applicable to submicrolithographic processes using ArFlight have not been found, thus far. As for inorganic ARCs, there havebeen reported no materials which can control the interference at the ArFwavelength, that is, 193 nm. As a result, active research has beenundertaken to develop organic materials which act as superb ARCs. Infact, in most cases of submicrolithography, photosensitive layers arenecessarily accompanied by organic ARCs which prevent the standing wavesand reflective notching occurring upon light exposure, and eliminate theinfluence of the back diffraction and reflection of light from lowerlayers. Accordingly, the development of such an ARC material showinghigh absorption properties against specific wavelengths is one of thehottest and most urgent issues in the art.

[0013] U.S. Pat. No. 4,910,122 discloses an ARC which is interposedunder photosensitive layers to eliminate defects caused by reflectedlight. The coating described therein can be formed thinly, smoothly anduniformly and includes a light absorbing dye which eliminates many ofthe defects caused by reflected light, resulting in increased sharpnessof the images in photosensitive materials. These types of ARCs, however,suffer from disadvantages of being complicated in formulation, extremelylimited in material selection and difficult to apply forphotolithography using Deep Ultraviolet (DUV) radiation. For example,the ARC of the above reference comprises 4 dye compounds, includingpolyamic acid, curcumin, Bixin and Sudan Orange G, and 2 solvents,including cyclohexanone and N-methyl-2-pyrrolidone. This multi-componentsystem is not easy to formulate and may intermix with the resistcomposition coated thereover, bringing about undesired results.

SUMMARY OF THE INVENTION

[0014] Therefore, it is an object of the present invention to overcomethe problems encountered in the prior art and to provide a novel organiccompound which can be used as an ARC for submicrolithography using 193nm ArF, 248 nm KrF and 157 nm F₂ lasers.

[0015] It is another object of the present invention to provide a methodfor preparing an organic compound which prevents the diffusion andreflection caused by the light exposure in submicrolithography.

[0016] It is a further object of the present invention to provide an-ARCcomposition containing such a diffusion/reflection-preventive compoundand a preparation method therefor.

[0017] It is a still further object of the present invention to providean ARC formed from such a composition and a preparation method therefor.

[0018] The present invention pertains to acrylate polymer resins whichcan be used as an ARC. Preferred polymer resins contain a chromophorewhich exhibits high absorbance at 193 nm and 248 nm wavelengths. Acrosslinking mechanism between alcohol groups and other functionalgroups is introduced into the polymer resins, so that a crosslinkingreaction takes place when coatings of the polymer resins are “hardbaked”, thereby greatly improving the formation, tightness anddissolution properties of the ARCs. In particular, optimum crosslinkingreaction efficiency and storage stability are realized in the presentinvention. The ARC resins of the present invention show superiorsolubility in all hydrocarbon solvents, but are of so high solventresistance after hard baking that they are not dissolved in any solventat all. These advantages allow the resins to be coated without anyproblem, and the coating prevents the undercutting and footing problemswhich can occur upon forming images on photosensitive materials.Furthermore, the coatings made of the acrylate polymers of the presentinvention are higher in etch rate than photosensitive films, improvingthe etch selection ratio therebetween.

DETAILED DESCRIPTION OF THE INVENTION

[0019] The ARC resins of the present invention are selected from thegroup consisting of acrylate polymers represented by the followinggeneral formulas I, II and III:

[0020] wherein,

[0021] R, R^(I), R^(II), and R^(III) are independently hydrogen or amethyl group;

[0022] R₀ is a methyl group or an ethyl group;

[0023] R₁ to R₉, which are the same or different, each representshydrogen, hydroxy, methoxycarbonyl, carboxyl, hydroxymethyl, or asubstituted or unsubstituted, linear or branched C₁-C₆ alkyl, alkane,alkoxyalkyl or alkoxyalkane;

[0024] x, y and z each is a mole fraction in the range from 0.01 to0.99; and

[0025] m and n are independently an integer of 1 to 4. In a preferredcompound of Formula I, m is 1 or 2 and n is an integer of 1 to 4. In apreferred compound of Formula II, m is 1 or 2 and n is an integer from 2to 4.

[0026] The polymers of the present invention are designed to providegreater absorbance at 193 nm and 248 nm wavelengths. To accomplish thisresult, a chromophore substituent which is able to absorb light at awavelength of 193 nm as well as 248 nm is grafted to the backbone of thepolymer.

[0027] The polymer of the general formula I, as illustrated in thefollowing reaction formula 1, can be prepared by polymerizing9-anthracenemethyl acrylate type monomers (I) and hydroxy alkylacrylatetype monomers (II) with the aid of an initiator in a solvent. Each ofthe monomers has a mole fraction ranging from 0.01 to 0.99.

[0028] (reaction formula 1)

[0029] wherein R, R¹, R₁ to R₉, x, y, m and n each is as defined above.

[0030] The polymers of the general formula II can be prepared in asimilar manner to the polymers of the general formula I, using9-anthracenemethyl acrylate type monomers (I), hydroxy alkylacrylatetype monomers (II) and methylmethacrylate monomers (III) at a molefraction of 0.01 to 0.99 for each monomer, as illustrated in thefollowing reaction formula 2:

[0031] (reaction formula 2)

[0032] wherein R, R^(I), R^(II), R₁ to R₉, x, y, z, m and n each is asdefined above.

[0033] The preparation of the polymer of the general formula III isillustrated in the following reaction formula 3. As shown, first,methacryloyl chloride (IV) is reacted with 4-hydroxy benzaldehyde (V) togive 4-formylphenylmethacrylate (VI) which is then polymerized with theaid of an initiator in a solvent, followed by substituting the4-formylphenyl groups with methanol or ethanol:

[0034] (reaction formula 3)

[0035] wherein R^(III) and R₀ each is as defined above.

[0036] For initiating the polymerization reaction for the polymers ofthe general formulas I, II and III, ordinary initiators may be used,with preference given to 2,2-azobisisobutyronitrile (AIBN),acetylperoxide, laurylperoxide and t-butylperoxide. Also, ordinarysolvents may be used for the polymerization. Preferably the solvent isselected from the group consisting of tetrahydrofuran, toluene, benzene,methylethyl ketone and dioxane.

[0037] Preferably, the polymerization of the polymers of the generalformulas I and II is carried out at 50-90° C.

[0038] The 9-anthracene alkyl acrylate type monomers (I) used to preparethe polymers of the general formulas I and II, are novel compounds whichcan be prepared by the reaction of 9-anthracene alcohol with acryloylchloride type compounds in a solvent, as illustrated in the followingreaction formula 4:

[0039] (reaction formula 4)

[0040] wherein R, R₁ to R₉, and n each is as defined above. Thehydroxyalkylacrylate type monomers (II) and methylmethacrylate monomers(III) used in the above reactions are commercially available, or theymay be prepared using known preparation methods.

[0041] Also, the present invention pertains to an ARC composition whichis based on a polymer mixture comprising the polymer of the generalformula I or II and the polymer of the general formula III, incombination with at least one additive selected from the groupconsisting of the anthracene derivatives shown in Table 1, below. TABLE1

[0042] In Table 1, R₁₁, R₁₂, R₁₃, R₁₄ and R₁₅ independently representhydrogen, hydroxy, hydroxymethyl, or substituted or unsubstituted linearor branched C₁-C₅ alkyl, alkane, alkoxyalkyl or alkoxyalkane.

[0043] ARC compositions according to the present invention may beprepared by (i) dissolving a polymer of the general formula I or II anda polymer of general formula III in a solvent to form a solution; (ii)optionally adding a compound selected from Table 1 to said solution, atan amount of 0.1 to 30% by weight, and (iii) filtering the solution.

[0044] Ordinary organic solvents may be used in preparing thecomposition, with preference given to ethyl 3-ethoxypropionate, methyl3-methoxy propionate, cyclohexanone and propylene methyletheracetate.The solvent is preferably used at an amount of 200 to 5000% by weightbased on the total weight of the ARC resin polymers used.

[0045] In another aspect of the present invention, an ARC is formed fromthe coating composition described above. After being filtered, thiscoating composition may be applied on a wafer in a conventional mannerand then “hard-baked”(i.e., heated to a temperature of 100-300° C. for10-1000 seconds) to form a crosslinked ARC. Quality semiconductordevices can be fabricated using ARCs of the present invention, becausethis crosslinked structure of the ARC offers optically stable lightexposure conditions when forming an image in the photosensitive layer.

[0046] It has been found that the ARCs of the present invention exhibithigh performance in submicrolithographic processes using 248 nm KrF, 193nm ArF and 157 nm F₂ lasers as light sources. The same was also truewhen 157 nm E-beams, EUV (extreme ultraviolet) and ion beams are used aslight sources.

[0047] A better understanding of the present invention may be obtainedin light of following examples which are set forth to illustrate, butare not to be construed to limit, the present invention.

EXAMPLE I Synthesis ofPoly[9-Anthracenemethylacrylate-(2-Hydroxyethylacrylate)] BinaryCopoloymer

[0048] Synthesis of 9-Anthracenemethylacrylate

[0049] 0.5 moles of 9-anthracene methanol and 0.5 moles of pyridine aredissolved in tetrahydrofuran and then, 0.5 moles of acryloyl chlorideare added. After completion of the reaction, the product is filtered outand extracted with ethyl acetate. The extract is washed many times withdistilled water and dried by distillation under vacuum, to give9-anthracenemethylacrylate, represented by the following chemicalformula 19. Yield 84%.

[0050] (chemical formula 19)

[0051] Synthesis ofPoly9-anthracenemethvlacrylate-(2-hydroxvethylacrylate)l binarycopolymer

[0052] In a 500 ml round-bottom flask are placed 0.5 moles of9-anthracenemethylacrylate and 0.5 moles of 2-hydroxyethylacrylate. Thismixture is added to 300 g of separately prepared tetrahydroftiran (THF)with stirring. Thereafter, in the presence of 0.1-3 g of2,2′-azobisisobutyronitrile (AIBN), the reaction is subjected topolymerization at 60-75° C. for 5-20 hours in a nitrogen atmosphere.After completion of the polymerization, the solution is precipitated inethyl ether or normal-hexane and the precipitate is filtered out anddried to produce apoly[9-anthracenemethylacrylate-(2-hydroxyethylacrylate)] copolymer, apolymer according to the present invention, represented by the followingchemical formula 20, at a yield of 83%.

[0053] (chemical formula 20)

EXAMPLE II Synthesis ofPoly[9-Anthracenemethylacrylate-(3-Hydroxypropylacrylate)] BinaryCopolymer

[0054] In a 500 ml round-bottom flask are placed 0.5 moles of the9-anthracenemethylacrylate synthesized in Example I and 0.5 moles of3-hydroxypropylacrylate. This mixture is added to 300 g of separatelyprepared THF with stirring. Thereafter, in the presence of 0.1-3 g ofAIBN, the reaction is subjected to polymerization at 60-75° C. for 5-20hours in a nitrogen atmosphere. After completion of the polymerization,the solution is precipitated in ethyl ether or normal-hexane and theprecipitate is filtered out and dried to produce apoly[9-anthracenemethylacrylate-(3-hydroxypropylacrylate)] copolymer, apolymer according to the present invention, represented by the followingchemical formula 21, at a yield of 82%.

[0055] (chemical formula 21)

EXAMPLE III Synthesis ofPoly[9-Anthracenemethylacrylate-(4-Hydroxybutylacrylate)] Copolymer

[0056] In a 500 ml round-bottom flask are placed 0.5 moles of9-anthracenemethylacrylate and 0.5 moles of 4-hydroxybutylacrylate. Thismixture is added to 300 g of separately prepared THF with stirring.Thereafter, in the presence of 0.1-3 g of AIBN, the reaction issubjected to polymerization at 60-75° C. for 5-20 hours in a nitrogenatmosphere. After completion of the polymerization, the solution isprecipitated in ethyl ether or normal-hexane and the precipitate isfiltered out and dried to produce apoly[9-anthracenemethylacrylate-(4-hydroxybutylacrylate)] copolymer, apolymer according to the present invention, represented by the followingchemical formula 22. Yield 81%.

[0057] (chemical formula 22)

EXAMPLE IV Synthesis ofPoly[9-Anthracenemethylmethacrylate-(2-Hydroxyethylacrylate)] BinaryCopolymer

[0058] Synthesis of 9-Anthracenemethylmethacrylate

[0059] 0.5 moles of 9-anthracene methanol and 0.5 moles of pyridine aredissolved in THF and then, 0.5 moles of methacryloyl chloride are added.After completion of the reaction, the product is filtered out andextracted with ethyl acetate. The extract is washed many times withdistilled water and dried by distillation under vacuum, to give9-anthracenemethylmethacrylate, represented by the following chemicalformula 23. Yield 83%.

[0060] (chemical formula 23)

[0061] Synthesis ofPoly9-anthracenemethylmethacrylate-(2-hydroxyethylacrylate)l binarycopolymer

[0062] In a 500 ml round-bottom flask are placed 0.5 moles of9-anthracenemethylmethacrylate and 0.5 moles of 2-hydroxyethylacrylate.This mixture is added to 300 g of separately prepared THF with stirring.Thereafter, in the presence of AIBN, the reaction is subjected topolymerization at 60-75° C. for 5-20 hours in a nitrogen atmosphere.After completion of the polymerization, the solution is precipitated inethyl ether or normal-hexane and the precipitate is filtered and driedto produce apoly[9-anthracenemethylmethacrylate-(2-hydroxyethylacrylate)] copolymer,a resin according to the present invention, represented by the followingchemical formula 24, at a yield of 79%.

[0063] (chemical formula 24)

EXAMPLE V Synthesis ofPoly[9-Anthracenemethylmethacrylate-(3-Hydroxypropylacrylate)] BinaryCopolymer

[0064] In a 500 ml round-bottom flask are placed 0.5 moles of the9-anthracenemethylmethacrylate synthesized in Example IV and 0.5 molesof 3-hydroxypropylacrylate. This mixture is added to 300 g of separatelyprepared THF with stirring. Thereafter, in the presence of 0. 1-3 g ofAIBN, the reaction is subjected to polymerization at 60-75° C. for 5-20hours in a nitrogen atmosphere. After completion of the polymerization,the solution is precipitated in ethyl ether or normal-hexane and theprecipitate is filtered and dried to produce apoly[9-anthracenemethylmethacrylate-(2-hydroxypropylacrylate)]copolymer, a polymer according to the present invention, represented bythe following chemical formula 25. Yield 81%.

[0065] (chemical formula 25)

EXAMPLE VI Synthesis ofPoly[9-Anthracenemethylmethacrylate-(4-Hydroxybutylacrylate)] BinaryCopolymer

[0066] In a 500 ml round-bottom flask are placed 0.5 moles of the9-anthracenemethylacrylate synthesized in Example IV and 0.5 moles of4-hydroxybutylacrylate. This mixture is added to 300 g of separatelyprepared THF with stirring. Thereafter, in the presence of 0.1-3 g ofAIBN, the reaction is subjected to polymerization at 60-75° C. for 5-20hours in a nitrogen atmosphere. After completion of the polymerization,the solution is precipitated in ethyl ether or normal-hexane and theprecipitate is filtered and dried to produce apoly[9-anthracenemethylmethacrylate-(4-hydroxybutylacrylate)] copolymer,a polymer according to the present invention, represented by thefollowing chemical formula 26, at a yield of 81%.

[0067] (chemical formula 26)

EXAMPLE VII Synthesis ofPoly[9-Anthracenemethylacrylate-(2-Hydroxyethylacrylate)-Methylmethacrylate]Ternary Copolymer

[0068] In a 500 ml round-bottom flask are placed 0.3 moles of9-anthracenemethylacrylate, 0.5 moles of 2-hydroxyethylacrylate and 0.2moles of methylmethacrylate. This mixture is added to 300 g ofseparately prepared THF with stirring, after which, in the presence of0.1-3 g of AIBN, the reaction was subjected to polymerization at 60-75°C. for 5-20 hours in a nitrogen atmosphere. After completion of thepolymerization, the solution is precipitated in ethyl ether ornormal-hexane and the precipitate is filtered and dried to produce apoly[9-anthracenemethylacrylate-(2-hydroxyethyl)-methylmethacrylate]copolymer, a polymer according to the present invention, represented bythe following chemical formula 27. Yield 80%.

[0069] (chemical formula 27)

EXAMPLE VIII Synthesis ofPoly[9-Anthracenemethylacrylate-(3-Hydroxypropylacrylate)-Methylmethacrylate]Ternary Copolymer

[0070] In a 500 ml round-bottom flask are placed 0.3 moles of9-anthracenemethylacrylate, 0.5 moles of 3-hydroxypropylacrylate and 0.2moles of methylmethacrylate. This mixture is added to 300 g ofseparately prepared THF with stirring, after which, in the presence of0.1-3 g of AIBN, the reaction was subjected to polymerization at 60-75°C. for 5-20 hours in a nitrogen atmosphere. After completion of thepolymerization, the solution is precipitated in ethyl ether ornormal-hexane and the precipitate is filtered and dried to produce apoly[9-anthracenemethylacrylate-(3-hydroxypropyl)-methylmethacrylate]copolymer, a polymer according to the present invention, represented bythe following chemical formula 28, at a yield of 82%.

[0071] (chemical formula 28)

EXAMPLE IX Synthesis ofPoly[9-Anyhracenemethylacrylate-(4-Hydroxybutylacrylate)-Methylmethacrylate]Ternary Copolymer

[0072] In a 500 ml round-bottom flask are placed 0.3 moles of9-anthracenemethylacrylate, 0.5 moles of 4-hydroxybutylacrylate and 0.2moles of methylmethacrylate. This mixture is added to 300 g ofseparately prepared THF with stirring, after which, in the presence of0.1-3 g of AIBN, the reaction is subjected to polymerization at 60-75°C. for 5-20 hours in a nitrogen atmosphere. After completion of thepolymerization, the solution is precipitated in ethyl ether ornormal-hexane and the precipitate is filtered and dried to produce apoly[9-anthracenemethylacrylate-( 4-hydroxybutyl)-methylmethacrylate]copolymer, a polymer according to the present invention, represented bythe following chemical formula 29. Yield 81%.

[0073] (chemical formula 29)

EXAMPLE X Synthesis ofPoly[9-Anthracenemethylmethacrylate-(2-Hydroxyethylacrylate)-Methylmethacrylate]Ternary Copolymer

[0074] In a 500 ml round-bottom flask are placed 0.3 moles of the9-anthracenemethylmethacrylate synthesized in Example IV, 0.5 moles of2-hydroxyethylacrylate and 0.2 moles of methylmethacrylate. This mixtureis added to 300 g of separately prepared THF with stirring, after which,in the presence of 0.1-3 g of A1BN, the reaction is subjected topolymerization at 60-75° C. for 5-20 hours in a nitrogen atmosphere.After completion of the polymerization, the solution is precipitated inethyl ether or normal-hexane and the precipitate is filtered and driedto produce apoly[9-anthracenemethylmethacrylate-(2-hydroxyethyl)-methylmethacrylate]copolymer, a polymer according to the present invention, represented bythe following chemical formula 30. Yield 82%.

[0075] (chemical formula 30)

EXAMPLE XI Synthesis ofPoly[9-Anthracenemethylmethacrylate-(3-Hydroxypropylacrylate)-Methylmethacrylate]Ternary Copolymer

[0076] In a 500 ml round-bottom flask are placed 0.3 moles of the9-anthracenemethylacrylate synthesized in Example IV, 0.5 moles of3-hydroxypropylacrylate and 0.2 moles of methylmethacrylate. Thismixture is added to 300 g of separately prepared THF with stirring,after which, in the presence of 0.1-3 g of AIBN, the reaction issubjected to polymerization at 60-75° C. for 5-20 hours in a nitrogenatmosphere. After completion of the polymerization, the solution isprecipitated in ethyl ether or normal-hexane and the precipitate isfiltered and dried to produce a poly[9-anthracenemethylmethacrylate-(3-hydroxypropyl)-methylmethacrylate] copolymer, a polymer according tothe present invention, represented by the following chemical formula 31,at a yield of 81%.

EXAMPLE XII Synthesis ofPoly[9-Anthracenemethylmethacrylate-(4-Hydroxybutylacrylate)-Methylmethacrylate]Ternary Copolymer

[0077] In a 500 ml round-bottom flask are placed 0.3 moles of the9-anthracenemethylacrylate synthesized in Example IV, 0.5 moles of4-hydroxybutylacrylate and 0.2 moles of methylmethacrylate. This mixtureis added to 300 g of separately prepared THF with stirring, after which,in the presence of 0.1-3 g of AIBN, the reaction is subjected topolymerization at 60-75° C. for 5-20 hours in a nitrogen atmosphere.After completion of the polymerization, the solution is precipitated inethyl ether or normal-hexane and the precipitate is filtered and driedto produce apoly[9-anthracenemethylmethacrylate-(4-hydroxybutyl)-methylmethacrylate]copolymer, a polymer according to the present invention, represented bythe following chemical formula 32. Yield 80%.

[0078] (chemical formula 32)

EXAMPLE XIII Synthesis ofPoly[9-Anthraceneethylacrylate-(2-Hdroxyethylacrylate)] Binary Copolymer

[0079] Synthesis of 9-Anthraceneethylacrylate

[0080] 0.5 moles of 9-anthracene ethanol and 0.5 moles of pyridine aredissolved in THF and then, 0.5 moles of acryloyl chloride are added.After completion of the reaction, the product is filtered out andextracted with ethyl acetate. The extract is washed many times withdistilled water and dried by distillation under vacuum, to give9-anthracenemethylacrylate, represented by the following chemicalformula 33. Yield 80%.

[0081] (chemical formula 33)

[0082] Synthesis ofPoly[9-anthraceneethylacrylate-(2-hydroxyethylacrylate)] copolymer

[0083] In a 500 ml round-bottom flask are placed 0.5 moles of9-anthraceneethylacrylate and 0.5 moles of 2-hydroxyethylacrylate. Thismixture is added to 300 g of separately prepared THF with stirring.Thereafter, in the presence of 0.1-3 g of AIBN, the reaction issubjected to polymerization at 60-75° C. for 5-20 hours in a nitrogenatmosphere. After completion of the polymerization, the solution isprecipitated in ethyl ether or normal-hexane and the precipitate isfiltered out and dried to produce apoly[9-anthraceneethylacrylate-(2-hydroxyethylacrylate)] copolymer, aresin according to the present invention, represented by the followingchemical formula 34, at a yield of 82%.

[0084] (chemical formula 34)

EXAMPLE XIV Synthesis ofPoly[9-Anthraceneethylacrylate-(3-Hydroxypropylacrylate)] BinaryCopolymer

[0085] In a 500 ml round-bottom flask are placed 0.5 moles of the9-anthraceneethylacrylate synthesized in Example XIII and 0.5 moles of3-hydroxypropylacrylate. This mixture is added to 300 g of separatelyprepared THF with stirring. Thereafter, in the presence of 0.1-3 g ofAIBN, the reaction is subjected to polymerization at 60-75° C. for 5-20hours in a nitrogen atmosphere. After completion of the polymerization,the solution is precipitated in ethyl ether or normal-hexane and theprecipitate is filtered out and dried to produce apoly[9-anthraceneethylacrylate-(3-hydroxypropylacrylate)] copolymer, apolymer according to the present invention, represented by the followingchemical formula 35, at a yield of 81%.

[0086] (chemical formula 35)

EXAMPLE XV Synthesis ofPoly[9-Anthraceneethylacrylate-(4-Hydroxybutylacrylate)] Copolymer

[0087] In a 500 ml round-bottom flask are placed 0.5 moles of9-anthraceneethylacrylate and 0.5 moles of 4-hydroxybutylacrylate. Thismixture is added to 300 g of separately prepared THF with stirring.Thereafter, in the presence of 0. 1-3 g of AIBN, the reaction solutionis subjected to polymerization at 60-75° C. for 5-20 hours in a nitrogenatmosphere. After completion of the polymerization, the solution isprecipitated in ethyl ether or normal-hexane and the precipitate isfiltered and dried to produce apoly[9-anthraceneethylacrylate-(4-hydroxybutylacrylate)] copolymer, apolymer according to the present invention, represented by the followingchemical formula 36. Yield 80%.

[0088] (chemical formula 36)

EXAMPLE XVI Synthesis of Poly[4-(1,1-Dimethoxymethyl)Phenylmethacrylate)]

[0089] Synthesis of poly[4-formyphenylmethacrylate]

[0090] In a 300 ml round-bottom flask, 31.3 g of (0.3 moles) ofmethacryloyl are completely dissolved in 200 g of THF by stirring and 26g of pyridine are added. To this solution 36.6 g (0.3 moles) of4-hydroxybenzaldehyde are added dropwise, after which these reactantsare allowed to react for 24 hours or longer. The product solution iswashed with deionized water to separate an aqueous layer from which thedesired compound is extracted and dried.

[0091] 0.4 moles of the 4-formylphenylmethacrylate thus obtained areplaced, together with 300 g of THF, in a 500 ml round-bottom flask and0.1-3 g of AIBN are added thereto with stirring. Polymerization isconducted at 60-75° C. for 5-20 hours in a nitrogen atmosphere. Aftercompletion of the polymerization, the solution is precipitated in ethylether or normal hexane and the precipitate is filtered and dried toprovide a poly[4-formylphenylmethacrylate] polymer at a yield of 80%.

[0092] Synthesis of poly[4-( 1,1 -dimethoxvmethvl)phenylmethacrylate]

[0093] In a 400 ml Erlenmeyer flask are placed 15 g of the polymerobtained above and 200 ml of THF and then, 100 g of methanol are added,together with 0.5 g of HCl, after which these reactants are allowed toreact at 60° C. for about 12 hours. The product solution is precipitatedin ethyl ether or normal hexane and the precipitate is filtered anddried to give poly[4-(1,1-dimethoxymethyl)phenylmethacrylate], a polymeraccording to the present invention, represented by the followingchemical formula 37. Yield 82%.

[0094] (chemical formula 37)

EXAMPLE XVII Synthesis of Poly[4-(1,1-Diethoxymethyl)Phenylmethacrylate]

[0095] In a 400 ml Erlenmeyer flask are placed 15 g of thepoly(4-formylmethacrylate synthesized in Example XVI and 200 ml of THFand then, 150 g of ethanol are added, together with 0.5 g of HCl, afterwhich these reactants are allowed to react at 60° C. for about 12 hours.The product solution is precipitated in ethyl ether or normal hexane andthe precipitate is filtered and dried to give poly[4-(1, 1-diethoxymethyl)phenylmethacrylate], a resin according to the presentinvention, represented by the following chemical formula 38. Yield 80%.

[0096] (chemical formula 38)

EXAMPLE XVIII Preparation of Arc

[0097] A polymer prepared in each of Examples I to XV and a polymerprepared in Example XVI or XVII are dissolved in propyleneglycolmethylether acetate (PGMEA). This solution, alone or in combination with0.1-30% by weight of at least one additive selected from the compoundsof the chemical formulas 1 to 18 in Table 1, is filtered, coated on awafer, and hard-baked at 100-300° C. for 10-1,000 sec to form an ARC. Aphotosensitive material may be applied on the ARC thus formed and imagedto ultrafine patterns in the conventional manner.

[0098] As described hereinbefore, the ARC of the present invention,which is obtained from a mixture comprising a polymer of the generalformula I or II and a polymer of the general formula III, alone or incombination with an additive of chemical formulas I to 18 in Table 1,contains chromophore substituents sufficient to exhibit absorbance atthe wavelengths useful for submicrolithography.

[0099] Particularly, the ARC of the present invention provides maximalcrosslinking reaction efficiency and storage stability. The ARC polymerresins of the present invention show superior solubility in allhydrocarbon solvents, but are of such high solvent resistance after hardbaking that they are not dissolved in any solvent at all. Theseadvantages allow the resins to be coated without any problem, and theresulting coating prevents undercutting and footing problems which mayoccur when forming images on photosensitive materials. Furthermore,coatings made of the acrylate polymers of the present invention arehigher in etch rate than photosensitive films, improving the etchselection ratio therebetween.

[0100] Thus, ARCs of the present invention can play an excellent role informing ultrafine patterns. For example, it can prevent the backreflection of light from lower layers or the surface of thesemiconductor element, as well as eliminate the standing waves caused bylight and the thickness changes in the photoresist layer itself, duringa submicrolithographic process using a 248 nm KrF, 193 nm ArF or 157 nmF2 laser. This results in the stable formation of ultrafine patternssuitable for 64M, 256M, 1G, 4G and 16G DRAM semiconductor devices and agreat improvement in the production yield.

[0101] The present invention has been described in an illustrativemanner, and it is to be understood the terminology used is intended tobe in the nature of description rather than of limitation. Manymodifications and variations of the present invention are possible inlight of the above teachings. Therefore, it is to be understood thatwithin the scope of the appended claims, the invention may be practicedotherwise than as specifically described.

What is claimed is:
 1. 1. A 9-anthracene alkylacrylate compound,represented by the following chemical formula 39:

(chemical formula 39) wherein, R¹ is hydrogen or —CH₃; R₁ to R₉, whichare the same or different, each represents hydrogen, hydroxy,methoxycarbonyl, carboxyl, hydroxymethyl, or a substituted orunsubstituted, linear or branched C₁-C₆alkyl, alkane, alkoxyalkyl oralkoxyalkane; and m is an integer of 1 to
 4. 2. A method for preparing a9-anthracene alkylacrylate compound which comprises reacting a9-anthracene alkylalcohol with an acryloyl chloride compound intetrahydrofuran, as shown in the following reaction formula 4:

(reaction formula 4) wherein, R is hydrogen or —CH₃; R₁ to R₉, which arethe same or different, each represents hydrogen, hydroxy,methoxycarbonyl, carboxyl, hydroxymethyl, or a substituted orunsubstituted, linear or branched C₁-C₆ alkyl, alkane, alkoxyalkyl oralkoxyalkane; and n is an integer of 1 to
 4. 3.4-formylphenylmethacrylate, having the structure of the followingchemical formula 40:

(chemical formula 40)
 4. A method for preparing4-formylphenylmethacrylate which comprises reacting methacryloylchloride with 4-hydroxybenzaldehyde.
 5. A polymer represented by thefollowing general formula I:

(general formula I) wherein, R and R¹, which are the same or different,each represents hydrogen or —CH₃; R₁ to R₉, which are the same ordifferent, each represents hydrogen, hydroxy, methoxycarbonyl, carboxyl,hydroxymethyl, or a substituted or unsubstituted, linear or branchedC₁-C₆ alkyl, alkane, alkoxyalkyl or alkoxyalkane; x and y each is a molefraction in the range from 0.01 to 0.99; and m is 1 or 2 and n is aninteger of 2 to
 4. 6. A polymer as set forth in claim 5, wherein R₁-R₉each is hydrogen; R¹ is hydrogen; x and y each is 0.5; and m is 1 and nis
 2. 7. A polymer as set forth in claim 5, wherein R₁-R₉ each ishydrogen; R¹ is hydrogen; x and y each is 0.5; and m is 1 and n is
 3. 8.A polymer as set forth in claim 5, wherein R₁-R₉ each is hydrogen; R¹ ishydrogen; x and y each is 0.5; and m is 1 and n is
 4. 9. A polymer asset forth in claim 5, wherein R₁-R₉ each is hydrogen; R¹ is —CH₃; x andy each is 0.5; and m is 1 and n is
 2. 10. A polymer as set forth inclaim 5, wherein R₁-R₉ each is hydrogen; R¹ is —CH₃; x and y each is0.5; and m is 1 and n is
 3. 11. A polymer as set forth in claim 5,wherein R₁-R₉ each is hydrogen; R¹ is —CH₃; x and y each is 0.5; and mis 1 and n is
 4. 12. A polymer as set forth in claim 5, wherein R₁-R₉each is hydrogen; R¹ is hydrogen; x and y each is 0.5; and m is 1 and nis
 2. 13. A polymer as set forth in claim 5, wherein R₁-R₉ each ishydrogen; R¹ is hydrogen; x and y each is 0.5; and m is 2 and n is 3.14. A polymer as set forth in claim 5, wherein R₁-R₉ each is hydrogen;R¹ is hydrogen; x and y each is 0.5; and m is 2 and n is
 4. 15. A methodfor preparing a copolymer (III) which comprises reacting a 9-anthracenealkylacrylate type monomer (I) with a hydroxyalkylacrylate type monomer(II) in the presence of an initiator in a solvent, as shown in thefollowing reaction formula 5:

(reaction formula 5) wherein, R; R₁ to R₉; and m and n have the meaningsset forth in claim
 5. 16. A polymer represented by the following generalformula II:

(general formula II) wherein, R, R^(I) and R^(II), which are the same ordifferent, each is hydrogen or —CH₃; R₁ to R₉, which are the same ordifferent, each represents hydrogen, hydroxy, methoxycarbonyl, carboxyl,hydroxymethyl, or a substituted or unsubstituted, linear or branchedC₁-C₆ alkyl, alkane, alkoxyalkyl or alkoxyalkane; x, y and z each is anmole fraction in the range from 0.01 to 0.99; and m is 1 or 2 and n isan integer of 2 to
 4. 17. A polymer as set forth in claim 16, whereinR₁-R₉ each is hydrogen; R¹ is hydrogen; x, y and z are 0.3, 0.5 and 0.2,respectively; and m is 1 and n is
 2. 18. A polymer as set forth in claim16, wherein R₁-R₉ each is hydrogen; R¹ is hydrogen; x, y and z are 0.3,0.5 and 0.2, respectively; and m is 1 and n is
 3. 19. A polymer as setforth in claim 16, wherein R₁-R₉ each is hydrogen; R¹ is hydrogen; x, yand z are 0.3, 0.5 and 0.2, respectively; and m is 1 and n is
 4. 20. Apolymer as set forth in claim 16, wherein R₁-R₉ each is hydrogen; R¹ is—CH₃; x, y and z are 0.3, 0.5 and 0.2, respectively; and m is 1 and n is2.
 21. A polymer as set forth in claim 16, wherein R₁-R₉ each ishydrogen; R¹ is —CH₃; x, y and z are 0.3, 0.5 and 0.2; and m is 1 and nis
 3. 22. A polymer as set forth in claim 16, wherein R₁-R₉ each ishydrogen; R¹ is —CH3; x, y and z are 0.3, 0.5 and 0.2, respectively; andm is 1 and n is
 4. 23. A method for preparing a copolymer (IV) whichcomprises reacting a 9-anthracene alkylacrylate type monomer (I), ahydroxyalkylacrylate type monomer (II) and methylmethacrylate (III) witheach other in the presence of an initiator in a solvent, as shown in thefollowing reaction formula 6:

(reaction formula 6) wherein, R, R^(I), and R^(III); R1 to R9; and m andn have the meanings set forth in claim
 16. 24. A polymer havingrepeating units of the following general formula III:

(general formula III) wherein, R^(III) is hydrogen or —CH₃ and R₀ is—CH₃ or —CH₂CH₃.
 25. A method for preparing a copolymer which comprisespolymerizing formylphenylmethacrylate to form a polymer and thenreacting said polymer with methanol or ethanol.
 26. A method as setforth in claim 15 or 23, wherein each of the monomers range, in molefraction, from 0.01 to 0.99.
 27. A method as set forth in claim 15 or23, wherein the initiator is selected from the group consisting of2,2-azobisisobutyronitrile, acetylperoxide, laurylperoxide, andt-butylperoxide.
 28. A method as set forth in claim 15 or 23, whereinthe solvent is selected from the group consisting of tetrahydrofuran,toluene, benzene, methylethyl ketone and dioxane.
 29. A method as setforth in claim 15 or 23, wherein the polymerization is carried out at atemperature of 50-90° C.
 30. An anti-reflective coating compositioncomprising a polymer of claim 5, 16 or
 24. 31. An anti-reflectivecoating composition as set forth in claim 30, further comprising ananthracene derivative.
 32. An anti-reflective coating composition as setforth in claim 31, wherein the anthracene derivative is selected fromthe group consisting of anthracene, 9-anthracene methanol, 9-anthracenecarbonitrile, 9-anthracene carboxylic acid, dithranol,1,2,10-anthracenetriol, anthraflavic acid, 9-anthraldehyde oxime,9-anthraldehyde,2-amino-7-methyl-5-oxo-5H-[1]-benzopyrano[2,3-b]pyridine-3-carbonitrile,1-aminoanthraquinone, anthraquinone-2-carboxylic acid,1,5-dihydroxyanthraquinone, anthrone, 9-anthryl trifluoromethyl ketone,9-alkylanthracene derivatives represented by the following chemicalformula 16, 9-carboxyl anthracene derivatives represented by thefollowing chemical formula 17, 1-carboxyl anthracene derivativesrepresented by the following chemical formula 18, and the combinationthereof:

(chemical formula 16) (chemical formula 17) (chemical formula 18)wherein, R₁₁, R₁₂, R₁₃, R₁₄, and R₁₅, which are the same or different,each represents —H, —OH, —CH₃, —CH₂OH, —(CH₂)pCH₃ wherein p is aninteger of 1 to 3, or a substituted or unsubstituted, linear or branchedalkyl, alkane, alkoxyalkyl or alkoxyalkane containing 1-5 carbon atoms.33. A method for preparing an anti-reflective coating composition, whichcomprises dissolving a polymer of claim 5, 16 or 24 in an organicsolvent and then adding thereto, an anthracene derivative additiveselected from the group consisting of anthracene, 9-anthracene methanol,9-anthracene carbonitrile, 9-anthracene carboxylic acid, dithranol,1,2,10-anthracenetriol, anthraflavic acid, 9-anthraldehyde oxime,9-anthraldehyde, 2-amino-7-methyl-5-oxo-5H-[1]-benzopyrano[2,3-b)]pyridine-3-carbonitrile, 1-aminoanthraquinone,anthraquinone-2-carboxylic acid, 1,5-dihydroxyanthraquinone, anthrone,9-anthryl trifluoromethyl ketone, 9-alkylanthracene derivatives of thefollowing chemical formula 16, 9-carboxyl anthracene derivatives of thefollowing chemical formula 17, 1-carboxyl anthracene derivatives of thefollowing chemical formula 18, and combinations thereof.

(chemical formula 16) (chemical formula 17) (chemical formula 18)wherein, R₁₁, R₁₂, R₁₃, R₁₄ and R₁₅, which are the same or different,each represents —H, —OH, —CH₃, —CH₂OH, —(CH₂)pCH₃ wherein p is aninteger of 1 to 3, or a substituted or unsubstituted, linear or branchedalkyl, alkane, alkoxyalkyl or alkoxyalkane containing 1-5 carbon atoms.34. A method as set forth in claim 33, wherein the anthracene derivativeadditive is used at an amount of 0.1 to 30% by weight.
 35. A method asset forth in claim 33, wherein the organic solvent is selected from thegroup consisting of ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate,cyclohexanone, and propyleneglycolmethyl ether acetate.
 36. Ananti-reflective coating composition, comprising a polymer of eitherclaim 5 or 16, and a polymer of claim
 24. 37. An anti-reflective coatingcomposition as set forth in claim 36, further comprising an anthracenederivative.
 38. An anti-reflective coating composition as set forth inclaim 37, wherein the anthracene derivative is selected from the groupconsisting of anthracene, 9-anthracene methanol, 9-anthracenecarbonitrile, 9-anthracene carboxylic acid, dithranol,1,2,10-anthracenetriol, anthraflavic acid, 9-anthraldehyde oxime,9-anthraldehyde,2-amino-7-methyl-5-oxo-5H-[1]-benzopyrano[2,3-b]pyridine-3-carbonitrile,1-aminoanthraquinone, anthraquinone-2-carboxylic acid,1,5-dihydroxyanthraquinone, anthrone, 9-anthryl trifluoromethyl ketone,9-alkylanthracene derivatives of the following chemical formula 16,9-carboxyl anthracene derivatives of the following chemical formula 17,1-carboxyl anthracene derivatives of the following chemical formula 18,and combinations thereof:

(chemical formula 16) (chemical formula 17) (chemical formula 18)wherein, R₁₁, R₁₂, R₁₃, R₁₄ and R₁₅, which are the same or different,each represents —H, —OH, —CH₃, —CH₂OH, —(CH₂)pCH₃ wherein p is aninteger of 1 to 3, or a substituted or unsubstituted, linear or branchedalkyl, alkane, alkoxyalkyl or alkoxyalkane containing 1-5 carbon atoms.39. A method for preparing an anti-reflective coating composition, whichcomprises dissolving a mixture of a polymer of either claim 5 or 16 anda polymer of claim 24 in an organic solvent and then, adding thereto ananthracene derivative additive selected from the group consisting ofanthracene, 9-anthracene methanol, 9-anthracene carbonitrile,9-anthracene carboxylic acid, dithranol, 1,2,10-anthracenetriol,anthraflavic acid, 9-anthraldehyde oxime, 9-anthraldehyde,2-amino-7-methyl-5-oxo-5H-[1]-benzopyrano[2,3-b]pyridine-3-carbonitrile, 1 -aminoanthraquinone,anthraquinone-2-carboxylic acid, 1,5-dihydroxyanthraquinone, anthrone,9-anthryl trifluoromethyl ketone, 9-alkylanthracene derivatives of thefollowing chemical formula 16, 9-carboxyl anthracene derivatives of thefollowing chemical formula 17, 1-carboxyl anthracene derivatives of thefollowing chemical formula 18, and combinations thereof.

(chemical formula 16) (chemical formula 17) (chemical formula 18)wherein, R₁₁,R₁₂, R₁₃, R₁₄ and R₁₅, which are the same or different,each represents —H, —OH, —CH₃, —CH₂OH, —(CH₂)pCH₃ wherein p is aninteger of 1 to 3, or a substituted or unsubstituted, linear or branchedalkyl, alkane, alkoxyalkyl or alkoxyalkane containing 1-5 carbon atoms.40. A method as set forth in claim 39, wherein the anthracene derivativeadditive is used at an amount of 0.1 to 30% by weight.
 41. A method asset forth in claim 39, wherein the organic solvent is selected from thegroup consisting of ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate,cyclohexanone, and propyleneglycolmethyl ether acetate.
 42. A method forforming an anti-reflective coating, in which an anti-reflective coatingcomposition of claim 30, 31, 36 or 37 is coated on a wafer and the waferis subjected to hard baking at 80-300° C.
 43. A semiconductor device,fabricated by using an anti-reflective coating of claim 30, 31, 36 or37.